L.A. Earthquake Could Be a ‘Foreshock’ for a Larger Quake

A seismologist briefing reporters this morning after a magnitude 4.4 earthquake struck the Los Angeles area said the shaker could be a "foreshock" with a larger quake waiting in the wings, the Los Angeles Times reports.

“Always the possibility that it’s a foreshock,” said Robert Graves, a seismologist with the U.S. Geological Survey, speaking at a news conference. Graves added that about 5% of earthquakes have an equal or larger shake that follows them, noting that it should be expected — if it is going to happen — within the next several hours, the Times reports.

The 6:25 a.m. (PT) earthquake that hit near the Encino section of Los Angeles was "the most significant shake in Southern California since a 5.5 earthquake hit Chino Hills in 2008," the story reports, citing Graves.

"Graves said there have been at least six aftershocks since the 6:25 a.m. earthquake," the report notes. "The largest so far has been a magnitude 2.7 earthquake that struck five miles northwest of Westwood."

Graves added: “Certainly we would expect more aftershocks.”

The Times adds: "Seismologists at the USGS have not yet determined exactly what fault this earthquake was on and Graves also said, ‘We’re continuing to analyze the data, but at this point, this seems to be what I would call a rather typical earthquake.’”

The piece notes that today’s main earthquake struck in "the northern edge of the Santa Monica Mountains area, a general area responsible for the uplifting of the range over many thousands of years."

Said Caltech seismologist Egill Hauksson: “The location is somewhat surprising. It’s within the Santa Monica Mountains. We have not seen seismicity in it in recent times. It has been dormant for quite some time.”

Graves noted that people reportedly felt today’s main quake as far as 50 miles from the epicenter.